Complexation of the cesium cation by macrocyclic polyethers in various solvents. A cesium-133 nuclear magnetic resonance study of the thermodynamics and kinetics of exchange

Journal Article · Fri Dec 31 23:00:00 EST 1976 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100532a015· OSTI ID:5593705

Mei, E; Popov, A I; Dye, J L

The formation constants for the complexation of Cs/sup +/ in six solvents by three crown ethers, 18-crown-6, dibenzo-18-crown-6, and dicyclohexyl-18-crown-6, were studied at 25/sup 0/C by cesium-133 NMR techniques. The solvents used, in the approximate order of decreasing first complexation constant for all crown ethers, were pyridine, acetone, propylene carbonate, acetonitrile, N,N-dimethylformamide, and dimethyl sulfoxide. In all solvents, 18-crown-6 formed both 1:1 and 2:1 (ligand to metal) complexes with enough difference between the complexation constants that the second constant could be determined. The formation of 2:1 complexes by the other two crown ethers was also indicated in most solvents, but the second complexation constant could only be measured for the dibenzo-18-crown-6 complex in pyridine. In many cases the first complexation constant was too large to measure by the NMR technique so that only lower bounds could be established. The rate of loss of the Cs/sup +/ ion from dicyclohexyl-18-crown-6 and from monobenzo-2,2,2-cryptand in propylene carbonate was measured as a function of temperature. The activation energy for the latter case (15 kcal mol/sup -1/) is substantially larger than for the crown ether complex (8.5 kcal mol/sup -1/). Although the chemical shifts of both Cs/sup +/ and its 1:1 complex with 18-crown-6 are strongly solvent dependent, the chemical shift of the 2:1 complex is independent of solvent, indicating that in the sandwich complex the cesium ion is effectively shielded from the solvent.

• Research Organization: Michigan State Univ., East Lansing
• OSTI ID: 5593705
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 81:17; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACETONE
ACETONITRILE
ALCOHOLS
ALKALI METAL COMPLEXES
AMIDES
AZINES
CARBONIC ACID DERIVATIVES
CESIUM COMPLEXES
CHEMICAL PREPARATION
COMPLEXES
DATA
DMSO
ENTHALPY
ENTROPY
EXPERIMENTAL DATA
FORMAMIDE
GLYCOLS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
KETONES
KINETICS
MAGNETIC RESONANCE
MOLECULAR STRUCTURE
NITRILES
NUCLEAR MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC POLYMERS
ORGANIC SULFUR COMPOUNDS
PHYSICAL PROPERTIES
POLYETHYLENE GLYCOLS
POLYMERS
PYRIDINES
REACTION KINETICS
RESONANCE
SOLVENT PROPERTIES
SULFOXIDES
SYNTHESIS
THERMODYNAMIC PROPERTIES